CompuWorld

"Hello, we’re excited to let you know that your account is one of a select few for which we’ve enabled a new feature called ad placements. Ad placements are groups of ad units that you can define and highlight to advertisers. Creating an ad placement is as easy as creating a custom channel, and ad placements will help you generate more revenue by increasing the visibility of your ad spaces to advertisers."

Did you get any such mail from google? It is not fake, that is a new adsense feature being introduced by google, but they are selecting few of there customers to test the feature for them.

In fact, what does new feature refer to? It is a feature that allows AdSense publishers to select a placement on their website that will be shown only to advertisers and are meant to generate more revenue and increase advertising.